AGRICULTURAL BOTANY. 225 



zol and tlie percentage of phosphorus in the extract estimated as magnesium 

 phosphate, have been repeated. The principal experiments were made with 

 Acer psciidoplatanus, but the results were confirmed by analysis of 18 other 

 plants. All showed an important phosphorus content in the ash. The authors 

 reassert the previous statement that phosphorus plays an important role in the 

 production of chloroiihyll. 



Lactic and alcoholic fermentation in plant tissues, J. Stoklasa {Atti 6. 

 Cong. Jnternaz. Chim. Appl, 3 (1906), pp. 885-890) .—The author gives a brief 

 account of studies on intramolecular respiration of beet roots, potato tubers, 

 beans, cucumbers, cherries, wheat, and barley, in which a lactic and alcoholic 

 fermentation was found to take place. This fermentation, it is claimed, is 

 due to an enzymic action, bacteria having nothing to do with it. 



The effect of light on germination, W. I\inzel (Ber. Dcut. Bot. GescIL, 26a 

 (1908). Xo. 2, pp. 105-1 lo, (U/iiis. //). — A study was made to determine the effect 

 of light and darkness, as well as of various colored lights, uiion the germination 

 -of seeds of a number of species of plants. 



In the case of Veronica seeds 100 per cent germinated under clear light and 

 under yellow light in 30 days, while germination was retarded under orange, red, 

 blue, and green light, in some cases less than 50 per cent germinating in 2 months. 



Similar investigations were conducted with the seeds of Poa, Nicotiana, 

 Drosera, Allium, Veratrum, and other plants. 



The stimulating action on germination of mixtures of colloidal solutions, 

 H. MiCHEELS and P. DeHeen (Acad. Roy. Bclff., Bui. CI. Sci.. 1907, Xo. 12, pp. 

 1027, 1028). — In continuation of previous work on the action of colloidal solu- 

 tions in stimulating germination (E. S. R., 18, p. 624), I'esults are given of 

 investigations carried on with colloidal solutions of platinum and of mag- 

 nesium and a mixture of equal parts of the two. The solutions were found to 

 exercise a stimulating effect on the germination of wheat, and the combined 

 !5ohition increased the iiercentage of germination very materially. 



The ascent of water in trees, A. J. Ewart (Phil. Trans. Roy. Sac. London, 

 Ser. B, 199 (1908), Ao. 258, pp. 3 'i 1-392, pi. 1, figs. 7).— In continuation of pre- 

 vious investigations into the physics of water flow through wood (E. S. R.. 

 17, p. 958), the author has carried on experiments on the ascent of water, 

 measuring it in maple and poplar trees, wistaria, and other plants. 



The author states that all his experiments tend to show that the continuous 

 ascent of water is only possible in living wood, the power of conduction being 

 rapidly lost on death, without any mechanical blocking of the vessels being 

 necessarily responsible for the change. Fi-om this he concludes that the 

 living cells in tall trees continually restore the conditions for the ascent of 

 water wherever these are affected by the excessive emptying of the vessels, 

 and decrease the resistance to flow as far as possible by maintaining continu- 

 ous water columns in at least parts of the wood. So long as these are present, 

 a pumping action on the part of the tree becomes necessary only in those 

 trees having a height of over 20 to 50 meters. Suspended columns of water 

 can not be maintained for any length of time in the vessels of tall trees without 

 the aid of the living cells of the wood. 



The energy required to pump water upward in the tallest trees is said to 

 represent only a small fraction of that produced by the daily photosynthetic 

 assimilation, and it is this feeble character and diffuseness of the pumping 

 action which renders it so difficult to demonstrate. 



Experiments on the suction and exudation of trees at different levels and 

 upon the influence of the entry of air and water under pressure showed that 

 no continuous suspended water columns or high internal tensions existed in 



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